The line had been standard during the XVIII Century but lost popularity after the French triumphs with columns during the Revolutionary Wars. The difficulty with advancing lines was their sensitivity to terrain and order. The irregularities of the terrain caused the ranks to become ragged, the battalion bowed in the middle and sometimes broke completely in half.
A line of two battalions on a battlefield would be halting to dress more frequently than one battalion. The long line made the troop more difficult to manoeuvre and to turn. For these reasons, commanders used lines only for short distances and over open terrain with no serious obstacles.
It was easier to attack with several battalion columns than with several battalion lines. General Antoine Henri Jomini wrote, "I have also seen attempts made to march deployed battalions in checkerwise order. They succeeded well; whilst marches of the same battalions in continous lines did not. The French, particularly, have never been able to march steadily in deployed lines... It maybe employed in the first stages of the movement forward, to make it more easy, and the rear battalions would then come into line with the leading ones before reaching the enemy ... for we must not forget that in the checkered order there are not two lines, but a single one, which is broken, to avoid the wavering and disorder observed in the marches of continous lines...
Suppose the attempt made to bring up 20 or 30 battalions in line, while firing either by file or by company, to the assault of a well defended position; it is not very probable they would ever reach the desired point, or if they did, it would be in about as good order as a flock of sheep."
Chlapowski writes, "He [General Dabrowski] took some battalions [of Polish infantry] out into the countryside and ordered them to perform certain manoeuvers. The movements in column went well, but battalions moving at the double in line with bayonets fixed were still very uneven and fell into bad disorder. The soldiers were not experienced enough yet to follow their marker with their eyes only, but instead turned their heads to the side as well. Once a few had turned their heads, their bodies could no longer walk in a straight line, steps became undeven and the whole line broke up as files either collided or diverged." (Chlapowski/Simmons - p 15)
The Prussian infantry of 1813-15 had similar problems. “As we (Prussians) neared the French batteries, Bulow attempted to protect our first wave, which was advancing in battalion masses, against the impact of the cannonballs by forming an ordinary line. This failed and the fast reorganization into battalion masses was the only means of preventing disorder. In addition, it proved that in the present employment of artillery and by the utilization of any terrain, an advance in combat with long, thin lines is impossible and should be stricken from the regulations.” (- General Boyen, after the battle of Gross-Beeren 1813)